[s3e19] I Am The Apocalypse -

This episode introduced the core cast that would eventually lead Chicago Med :

(Laurie Holden): A skilled trauma surgeon. Aftermath & Relationship Beats

A patient enters the ER claiming to carry a deadly airborne virus (revealed later as Marburg) and detonates a grenade .

In the wake of the trauma, Dawson and Casey share a romantic reconciliation at Molly’s, though the stability of their relationship remains a lingering question.

(Yaya DaCosta): An ER nurse with a past connection to Severide.